Dean Chambers Goes Old School Bircher »« Freedom: They Keep Using That Word…

Study Concludes Epigenetic Cause of Homosexuality

A new study in the Quarterly Review of Biology by a group of international researchers has concluded what I have long assumed to be true, that the primary cause of homosexuality is epigenetic and it is largely locked in during gestation.

Writing in The Quarterly Review of Biology, researchers William Rice, a professor at the University of California, Santa Barbara, and Urban Friberg, a professor at Uppsala University in Sweden, believe that homosexuality can be explained by the presence of epi-marks — temporary switches that control how our genes are expressed during gestation and after we’re born.

Specifically, the researchers discovered sex-specific epi-marks which, unlike most genetic switches, get passed down from father to daughter or mother to son. Most epi-marks don’t normally pass between generations and are essentially “erased.” Rice and Friberg say this explains why homosexuality appears to run in families, yet has no real genetic underpinning…

To reach this conclusion, Rice and Friberg created a biological and mathematical model that charted the role of epigenetics in homosexuality. They did so by applying evolutionary theory to recent advances in the molecular regulation of gene expression and androgen-dependent sexual development…

Normally, sex-specific marks that are triggered during early fetal development work to protect boys and girls in the womb from undergoing too much natural variation in testosterone, which should normally happen later in a pregnancy. Epigenetic processes prevent female fetuses from becoming masculinized when testosterone exposure gets too high, and vice versa for males.

Moreover, epi-marks also protect different sex-specific traits from swinging in the opposite direction; some affect the genitals, and others may affect sexual orientation. These epi-marks can be transmitted across generations from fathers to daughters, or mothers to sons.

Two caveats: First, I haven’t read this study and I’m not the best person to evaluate its validity if I had. I’d be very curious to hear the opinions of geneticists who have seen the study and can lend some expertise in understanding and evaluating it. Second, I would bet that this is hardly the end of the matter. I doubt that there is a single cause to homosexuality, though it has long seemed obvious to me that when someone says “well if homosexuality is genetic, why haven’t we found the gene that causes it” to be vastly oversimplified. With my admittedly limited understanding, it has long made sense that epigenetics is more important here than the idea of finding a specific gene that determines whether a person is gay or straight.

One more caveat: Ultimately, I don’t care whether the cause is genetic, epigenetic or otherwise. Even if the bigots were right and homosexuality was entirely a personal choice, like whether to wear bell bottoms or learn how to speak Spanish, it wouldn’t change my conclusion that everyone should be treated equally regardless of their sexual orientation or gender expression.

Comments

  1. MikeMa says

    I agree with Ed that it doesn’t matter whether the homosexuality has a nature or nurture source. Discrimination is wrong. The study should, if well done, close down some of the hater arguments and ought to shut down the gay reversion clinics completely.

  2. John Hinkle says

    And the gay “reversion therapists” out there will throw up there hands and say, “Well, there you have it. We were wrong. Guess we’ll stop attempting to turn gay people straight because not only are they born that way, this so called therapy probably causes them great suffering. Boy do I feel stupid.”
     
    Right?

  3. =8)-DX says

    One more caveat: Ultimately, I don’t care whether the cause is genetic, epigenetic or otherwise. Even if the bigots were right and homosexuality was entirely a personal choice, like whether to wear bell bottoms or learn how to speak Spanish, it wouldn’t change my conclusion that everyone should be treated equally regardless of their sexual orientation or gender expression.

    I’m not sure about that. Seems to me as if homosexuality would be something different then. (Requiring equal rights, of course!) I think we’d have lost something – I don’t think humans would have that strong sexual and romantic drives if orientation were only cultural.

  4. Sastra says

    John Hinkle #2 wrote:

    And the gay “reversion therapists” out there will throw up there hands and say, “Well, there you have it. We were wrong. Guess we’ll stop attempting to turn gay people straight because not only are they born that way, this so called therapy probably causes them great suffering. Boy do I feel stupid.”

    No they won’t — but based on their own reasoning, they probably shouldn’t , even if this study proves valid. After all, their real concern is that homosexuality is wicked and harmful. A genetic or epigenetic explanation wouldn’t rule out the value or efficiency of therapy, would it? I mean, consider how we’d approach this issue if they found an inborn epigentic cause for being a thief — or for hoarding. You might not be able to eliminate the tendency, but you’d certainly look for some learned skills to mitigate or control it.

    The real problem the reversion therapists ought to have is coming up with an explanation for why, if homosexuality is sinful, God would deliberately create people with a special propensity for this sin. It would seem to take away the whole idea of free will moral responsibility for choices.

    But I wouldn’t hold out much hope for cognitive dissonance here. The faithful have a long and revered practice of reconciling why God hands out different “challenges” to different people and therefore ends up punishing those who failed to do the right thing when under great duress and rewarding those who did the right thing in easy circumstances. It’s still fair because we KNOW it must be fair. Take the result and work backwards in assigning total blame to the wrongdoers.

    “God never gives you more than you can handle.” If you could have fought against acting on a natural urge then you SHOULD have fought against acting on a natural urge. Case closed.

    As Ed points out, the real issue here is that being gay causes no harm. It doesn’t matter how much “choice” we have.

  5. laurentweppe says

    One more caveat: Ultimately, I don’t care whether the cause is genetic, epigenetic or otherwise.

    But you forget one thing: neither do the bigots: if homosexuality ends up being demonstrated as being of genetic origins, the bigots who keep claiming that “it is a choice” will jump on the eugenistic bandwagon faster than you can say “wingnut”.

  6. valhar2000 says

    Ultimately, I don’t care whether the cause is genetic, epigenetic or otherwise.

    I wish more people took this position. When talking about civil rights for gay people, nature vs. nurture is a red herring.

  7. yoav says

    I only had a quick look at the paper but from that it seem that it doesn’t actually show an epigenetic regulation of homosexuality. all they have is a mathematical model that show that if the assumption they make, I.e

    1. A subset of inherited epigenetic marks are associated with homosexuality
    2. These mark affect the way the developing embryo react to changes in androgen levels
    3. The different response is the causal element for homosexuality

    are correct then epigenetic differences can explain sexual orientation. However they have not demonstrated that any of these assumptions is actually true so at this point it’s no more then a theoretical mathematical, which while interesting in the abstract, say absolutely nothing as to how things actually work in reality.

  8. Draken says

    The real problem the reversion therapists ought to have is coming up with an explanation for why, if homosexuality is sinful, God would deliberately create people with a special propensity for this sin. It would seem to take away the whole idea of free will moral responsibility for choices.

    But fundies, at least some of them, have no qualms blaming demonic influences if they get caught in painful situations. It wasn’t me, it was teh Satan.

  9. says

    The study should, if well done, close down some of the hater arguments and ought to shut down the gay reversion clinics completely.

    Yup, because if history has taught us anything, it’s that ideology (particularly religious ideology) always changes in the face of settled science.

  10. naturalcynic says

    So the old scrawled on a restroom trope that “Mommy made me a homosexual and daddy made her a lesbian” is true. [I know, if if I give her the yarn, will she make me one too] But, just not in the original sense. How many parents will feel guilty – I hope none.

  11. gridironmonger says

    Impending wingnut reactions/misinterpretations/misrepresentations:

    It’s epigenetics… therefore it’s environmental… therefore children are being “turned gay”
    or
    Okay, it is not genetic… therefore it is a choice
    or
    There is a biological basis which begins in utero… therefore it is a disorder/disease to be prevented or treated

    They always end up in the same place, no matter where they start from.

  12. anubisprime says

    It will have very little effect on the haters 4 jeebus crew.
    Inconvenient things like scientific study and conclusions are best left out of the homophobic rants they depart on.
    Besides they are preaching to folks that with the best will in the world would not understand the context of such a study as highlighted here anyway, it wouod confuse them terribly.
    These folk make decisions and form bigotries based on their own personal fears and ignorance.

    In the main they are very content with the ‘life choices’ explanation, it tends to keep their delusions front and centre and gives the crowd someone to feel ‘morally’ superior to.
    They will not drop that little fillip to their rather tawdry and righteous lives, not for all the scientific studies in Christendom!
    And the purveyors of such loony baloney do not want to lose income, kindda shooting themselves in the ass if they say…’OK me bad and jeebus drooling has no real effect’ , yeah right!
    Making money outta fundies means giving them what they want to hear, the fundie rank and file have no interest in homosexuality being beyond the control of the ‘misguided’, that means that gawd’ plays tricks or that…gasp pearl clutch…he meant those folks to be ghey, but that leaves the ‘wholly babble’ as an erroneous lead.

    Not worth contemplating really that could cause a lot of red faces around the church so as you were…them’s ‘teh ghey’s’ are going to hell!…you see that solves everything and the deluded can sleep soundly at night.

  13. says

    I know, if if I give her the yarn, will she make me one too

    My mom made me a sweater for *mas. I was hoping she’d make me a screamer or a moaner, but a sweater’s OK…

  14. left0ver1under says

    Where’s the surprise? We evolved from single gendered bisexual creatures, it shouldn’t shock that remnants of DNA make same sex attraction possible.

    The only question that I’d like to know is why there are more (or appear to be more) gay men than lesbian women. I suspect it has something to do with foetal development. Gay males change physically in the womb and don’t change which gender they will be attracted to, while lesbians change attraction but not their gender. And that the first is more likely to happen than the second.

  15. says

    If they ever find a way to detect some kind of marker that was predictive of the eventual sexuality of the child while still in the womb, it would certainly cast the abortion debate in a different light — likely on both sides.

  16. says

    Tacitus,

    Are you familiar with the uproar associated with Michael Bailey’s (Northwestern) popular press book about transgender persons?

  17. Midnight Rambler says

    The study doesn’t conclude; it hypothesizes. The epigenetic idea could potentially be right because it is consistent with the data we have so far (notably, correlation in twins but not precisely in identical twins, and failure to find any DNA differences associated with homosexuality). But they don’t have any direct evidence of epi-marks. They do predict, though, that those should be found, and in regulators of specific genes.

    The paper is open access, and can be found here: http://www.jstor.org/stable/10.1086/668167

  18. jamessweet says

    I wish more people took this position. When talking about civil rights for gay people, nature vs. nurture is a red herring.

    I think it’s less of a red herring, and more of a smart tactical move. (Note that the tactical benefit of the apparent fixedness of sexual orientation would be irrelevant if it weren’t at least mostly true) We’re at a point in history now where more and more people should be saying what Ed said, but there is value in playing the “nature” card in terms of changing minds in the short term. Now that people are more accepting in general, you’re right, I think some switching of gears is in order — not least because there are many people (the minority, to be sure, but a nontrivial minority) for whom the traditional narrative of fixed straight/gay orientation just doesn’t fit.

  19. vmanis1 says

    This may well be useful and good science, I don’t know enough about genetics to know whether there really is anything to their hypothesis. (I’m a computer scientist, I thought cold fusion was real :). However, I honestly don’t think it would have any effect on haters, or even inoculate less-knowledgeable people against homophobic hate.

    The problem is that the haters already have their story together, and have had it for years. There is a distinction, they say, between homosexual inclinations and homosexual acts, and the goal of both treatment and religious counselling is to help the homosexually-inclined person from committing such acts. An epigenetic cause may explain or at least mark the cause of the inclination, but this then gives more urgency, they would say, into helping that individual abstain from the acts, which are of course just like murder (paging Justice Scalia…).

    It’s only when people learn to judge homosexual acts by the same criteria as they judge heterosexual ones that support for marriage equality and non-discrimination begins to rise. I don’t think that inclination is an issue, sadly.

  20. Ichthyic says

    Two caveats: First, I haven’t read this study

    *headdesk*

    sorry Ed, but that’s not an acceptable excuse from a journalist.

    it was NOT a hard paper to read.

  21. Ichthyic says

    …adding to what Yoav said at #8, the paper itself notes a long history of studies strongly supporting that sexuality is a heritable trait, but that there should be expected tighter variance than is seen between twins in twin studies.

    there are a lot of other ways to explain why the variance might not be tight in twin studies than epigenetics.

    this is an interesting hypothesis at this point, nothing more.

  22. John Horstman says

    A few notes on framing as well:
    1) I am yet to hear of a study attempting to find out what causes heterosexuality. The perspective here posits heterosexuality as the default state and then attempts to explain homosexuality as a deviance from that norm. This has the possibility of biasing the results by implicitly restricting the scope of (in this case epigenetic) data correlated to whether individuals identify as homosexual.
    2) The populations being studied are located within a specific historical-cultural context that allows for discourses such as homosexual desire to exist in the first place. Without a specific (clearly cultural, as there are differences across time and space) conception of sex/gender and sexuality, the conceptualization of homosexuality itself isn’t possible, so even if the epigenetic model proves accurate, it can still only be said to explain the ’cause’ of homosexuality within a particular historical-cultural context. This leads us to…
    3) The posited model relies on self-reporting of some degree same-sex sexual attraction attraction to define the variant group. This rests on a number of culturally-constructed frameworks, chiefly governing how people identify the sex/gender of sexual partners and how people identify sexual desire (versus non-sexual desire or sexual activity without desire – as may be the case, for example, for sex workers – or sexual desire that does not position sex/gender as the primary determinant – how, for example, might the study conceive of people whose primary sexual expression centers on the idea of sexual submission irrespective of the gender of the dominant partner? How does the study handles cases of ‘situational homosexuality’, where, for example, an exclusively same-sex environment allows for only the possibility of same-sex oriented sexual desire and expression, such that individuals who might experience only other-sex desire in mixed-sex environments experience same-sex desire as a function of the lack of other-sex persons whom possibly could be desired?). When the division of studied populations into comparative groups depends entirely on cultural discourses, an exclusively-biological model inevitably fails to actually explain the studied trait.

    I have no objection to the idea that there may exist biological factors that predispose certain sexual orientations and perhaps even entirely determine them within a given cultural framework of sex/gender/sexuality, but describing these factors as themselves causative serves to essentialize (and presuppose) particular conceptions of sex/gender/sexuality and desire that are by no means essential, ‘natural’ (whatever that means), nor universal. This gives rise to a model that at best cannot be generalized beyond the cultural context(s) of the studied populations and at worst, given the wide variation in socialization of individuals within what we would define as a given cultural context, isn’t even accurate within the context(s) of the culture(s) of the studied populations.

    TL;DR version: attempting to find a generalizable biological model of homosexuality is an impossible project from the start, as such a project necessarily assumes non-universal models of things like sex, gender, sexuality, and desire.

  23. says

    Ichthyic wrote:

    sorry Ed, but that’s not an acceptable excuse from a journalist.

    I haven’t been a journalist in over a year now. And I didn’t know it was available publicly. I wasn’t making an excuse, acceptable or otherwise; I was just making a simple statement of fact. If I was analyzing the actual findings of the paper, I would obviously have to read it first. But I wasn’t doing that.

  24. dingojack says

    John Horstman
    While I appreciate your caution, there are a few things I think need to be fisked:

    “The perspective here posits heterosexuality as the default state and then attempts to explain homosexuality as a deviance from that norm”.

    Since the majority of humans worldwide seem to identify as heterosexual, and that such a sexual orientation has distinct individual advantage in ‘fitness’ from an evolutionary point of view, it would be a parsimonious assumption that heterosexuality is the default. Do you have evidence to suggest the contrary?

    “Without a specific (clearly cultural, as there are differences across time and space) conception of sex/gender and sexuality, the conceptualization of homosexuality itself isn’t possible,”

    You are confusing the name with the thing itself. If the word for ‘homosexual’ was expunged from every language on the planet do you seriously think the desire for one’s own sex would vanish too? Desire is a real thing, whether it is named or not.

    Also I have to question whether homosexuality is a cultural construct. There are thousands, possible tens of thousand of cultures across the Earth (in time and space), notwithstanding Ahmadinejad’s pronouncements, do you imagine there is a culture without homosexuality? For that matter, out of the tens of thousands of cultures (across time and space) have you ever heard of a culture entirely without heterosexuality? I can only think of two (and even then I am not be too certain) . Why would this be, if sexual desire is shaped by culture? Wouldn’t one expect a binomial distribution of some form?

    “The posited model relies on self-reporting of some degree same-sex sexual attraction attraction to define the variant group”.

    It is measuring sexual desire, not sexual activity, the two are not the same. And how else would you suggest measuring sexual desire? There are intrusive tests but they are not practical with a large enough sample size and may not be measuring sexual desire, merely autonomic responses.

    “How does the study handles cases of ‘situational homosexuality’, where, for example, an exclusively same-sex environment allows for only the possibility of same-sex oriented sexual desire and expression, such that individuals who might experience only other-sex desire in mixed-sex environments experience same-sex desire as a function of the lack of other-sex persons whom possibly could be desired?). ”

    Again, you are confusing desire with activity. The study is measuring desire, regardless of activity, or lack of activity, so this is not really an issue.

    You seem to be assuming that sexuality is defined into two groups, it isn’t, it’s considered as being a continuum from one extreme to the other.

    Otherwise, a very interesting post.
    Dingo

  25. paulg says

    We have nothing to lose by conducting the research. We may not be close to the entire truth, but we’ll never come to an adverse conclusion, as in “holy shit! it’s a choice after all!”. How do I know? I’m gay, and have been forever. Forever. There was no choice, it’s not an abstract argument. It’s very personal, and i really, really want to know the answers, and it doesn’t help that I’m a biology geek. My brain is wired to be attracted to guys, the same way a girl is usually wired to be attracted to guys. Why? It’s just awesome (now, intellectually. It sucked growing up).

  26. bad Jim says

    Isn’t it reasonable to assume that humans have been, broadly speaking, more or less the same for the last few thousands of years?

    Sexual practices are pretty variable, but historical accounts are more or less compatible with the state of affairs we see today, predominantly heterosexual, with a significant homosexual minority and a group of indeterminate size of indeterminate preference.

    The cultural warriors are panicked, perhaps, that they might be in the third bucket and their steely resolve is the only thing between them and everything they fear could go wrong with the world.

    Maybe we should promote the idea that guns are a gay thing.

  27. says

    The only question that I’d like to know is why there are more (or appear to be more) gay men than lesbian women. I suspect it has something to do with foetal development. Gay males change physically in the womb and don’t change which gender they will be attracted to, while lesbians change attraction but not their gender. And that the first is more likely to happen than the second.

    I’m not sure this is true, first of all the number of people identifying as other than straight has been increasing along with acceptability and the difference in gay versus lesbian has been shrinking. Also women are actually slightly more likely to identify as LGBT than men. http://www.gallup.com/poll/158066/special-report-adults-identify-lgbt.aspx I think the difference may be in that more women identify as bisexual* than as lesbian while very few men do. Just a personal anecdote: The number of openly bisexual women I know is probably an order of magnitude larger than the number of openly bisexual men I know. Perhaps men are less likely to be bisexual but I think you can’t discount that it’s still far less acceptable for men to identify as bisexual (and the disapproval comes from both the gay and straight community).

    *for clarity of argument I’m grouping pansexual under bisexual and sticking to discussing just cisgender folks because talking about non-gender binary would make this too long for a comment.

  28. left0ver1under says

    Naodi, mine was just a reasonable guess based on limited knowledge and no expertise. I have no problem admitting being wrong.

    Maybe the reason we hear more about gay men than women is the same reason we hear more about straight men than women: job and wage discrimination, who has more disposable income.

  29. left0ver1under says

    And excuse the typo on your name. I’m a lefty and often hit left side keys ahead of the right.

  30. dingojack says

    I thought the reason we hear more of gay men rather than gay women is the age-old assumption that women don’t have any sexuality, outside that which men assign to them.
    Yep, plain old misogyny (of course I could be completely wrong – although I doubt it).
    Dingo

  31. says

    @32 & @34 A bit of both probably comes into play, until very recently the number of gay men was a good deal higher than the number of lesbians (and it still is higher but the number of bisexual women even it out) and that is probably because of the view that women aren’t as sexual as men and that women need a man to provide for them. These cultural factors are also why you see fewer and fewer LGBT identified people the older you go (and this can’t just be explained by the heavy toll AIDs took because you also see fewer lesbians).

Trackbacks

Leave a Reply